How does what people eat affect their chances of getting cancer? Some new answers may be hidden in the millions of bacteria that live in one’s gut.

These bacteria make up the gut microbiome – the largest collection of bacteria in the body. It starts forming when people are born, then grows and changes as they age over time. Diet sustains these bacteria. In turn, the bacteria help digest food and absorb essential vitamins and nutrients.

Carrie Daniel-MacDougall, Ph.D., M.P.H., is a nutritional epidemiologist at MD Anderson. She will soon begin studies to learn more about how a person’s diet and microbiome jointly contribute to the risk of obesity and cancer.

Microbiome Research Uncovers Clues

“Having a healthy mix of gut bacteria may lower a person’s risk of obesity or weight gain,” Daniel-MacDougall said. “Obesity is a known risk factor for many cancers, including colorectal cancer.”

Gut bacteria play a vital role in how much energy or calories the body extracts from food. They also help decide how many calories to store as fat.

“A lot of unknowns exist about which bacteria make up an ideal microbiome and which are truly harmful,” Daniel-MacDougall said. “But, we are learning that a diverse community of gut bacteria is beneficial to a person’s health.”

Keep a Healthy Diet Rich in Plant Foods

“A diet that includes a variety of plant foods seems to fill your body with a healthy balance of bacteria,” Daniel-MacDougall said.

Plant foods, like fruits, beans and vegetables, also tend to be rich in fiber. And, fiber helps nurture a robust community of gut bacteria. Eating a variety of fiber-rich plant foods can also help reduce risks for many cancers, including colorectal cancer.

Include Healthy Prebiotic and Probiotic Foods

Eating prebiotic and probiotic foods may introduce new bacteria in the body. It also can change existing bacteria to ensure a healthy mix.

Prebiotic foods feed the bacteria already living in the gut. They include asparagus, bananas, oatmeal and beans or legumes.

Probiotic foods contain live bacteria. It is considered “good” bacteria because it helps prevent the growth of harmful bacteria in the gut. Yogurt with live or active cultures is a probiotic food.

Stick with a Stable Diet

“It’s your long-term choices that matter most when it comes to a healthy microbiome and lowering your cancer risk,” said Daniel-MacDougall. “So, the first step is to choose a healthy diet that satisfies you. Then, you’ll be more likely to stick with it over time.”

Visit www.mdanderson.org/focused for additional tips on health and exercise.